Three-dimensional (3-D) printing, also known as additive manufacturing, is a rapidly growing technology area that operates by depositing small droplets or streams of a melted or softened printing material in precise deposition locations under the control of a computer. Deposition of the printing material results in gradual, layer-by-layer buildup of a printed object, which can be in any number of complex shapes. At present, additive manufacturing processes are largely used for rapid prototyping purposes, but there is significant interest in extending these techniques to mass manufacturing. While printed prototypes need not necessarily be entirely functional or mechanically robust, mass manufactured objects need to be. At present, additive manufacturing processes do not yet have effective solutions for these and several other issues, as discussed hereinafter.
Polymers are among the more commonly used printing materials in additive manufacturing processes, although non-polymeric printing materials can be used in some instances. One problematic feature of polymer-based printing materials is that most polymers are not electrically conductive. When electrical conductivity of a finished object is necessary, the poor electrical conductivity of polymers can limit the breadth of printed objects that can be suitably produced using additive manufacturing techniques. Polymers can also lack sufficient mechanical strength and thermal conductivity for some high-performance applications.
There has been ongoing interest in incorporating carbon nanotubes and other nanomaterials within polymer composites due to the ability of these nanomaterials to convey electrical conductivity to an otherwise non-conductive polymer matrix, as well as to improve mechanical strength and other properties. Although some success has been realized in incorporating carbon nanotubes into polymer matrices, the carbon nanotubes are often not effectively dispersed from one another and compositional heterogeneity frequently results. Among other undesirable factors, compositional heterogeneity can lead to structural weak points in the composite.
In general, the incorporation of carbon nanotubes into a polymer significantly increases the glass transition temperature of the resulting polymer composite. The increased glass transition temperature can approach or exceed the decomposition temperature of the polymer itself, which can make carbon nanotube polymer composites difficult or impossible to use in conventional additive manufacturing processes. In addition, the compositional heterogeneity of many carbon nanotube polymer composites remains an ongoing concern for their potential use in forming printed objects, especially for high-performance applications.
In view of the foregoing, improved materials for use in additive manufacturing processes would be highly desirable in the art. The present disclosure satisfies the foregoing need and provides related advantages as well.